1 . Field of the Invention
The present invention relates generally to aluminum hull boats. More particularly, the present invention relates to an extruded aluminum running surface for improving the performance of aluminum hull boats.
2 . Background of the Invention
In the process of manufacturing aluminum hull boats, the boat hull is typically bent and formed to a desired shape with the use of a hydraulically actuated press break. As the press break bends the aluminum metal to form the running surfaces, strakes, and other hull structure, the metal inherently forms a rounded corner where it is bent. Water will naturally flow in the direction of least resistance. During high speed operation of the boat as water migrates outwardly from beneath the boat""s running surfaces, the rounded corners defining the running surface edges allow the water to remain in contact with the boat as the water follows the low resistive path along the curved edge. This process results in hydrodynamic drag which reduces the boat""s performance characteristics, including speed, fuel efficiency, range, hole shot performance, and manueverability.
Therefore, there is a need for an improved aluminum running surface, and method of manufacturing the same, for an aluminum hull boat.
The present invention eliminates the difficulties and disadvantages of the prior art by providing an aluminum boat hull having a bow, a transom, a centerline, and an undersurface in contact with the water when the boat is at rest. The boat hull includes an aluminum running pad fabricated by a process of extrusion. The running pad includes a lower planing element extending from a first end to a second end. At least a portion of the lower planing element is in contact with the water when the boat is at planing speed. The lower planing element is further defined by opposed first and second lateral edges, which are preferably parallel with the boat centerline and symmetrically offset therefrom. The running pad further includes a pair of sidewalls extending from the lateral edges to the boat""s undersurface. During the extrusion process, the lower planing element and the sidewalls are efficiently formed as a single extruded aluminum part with the lower planing element transitioning sharply to the sidewalls at the lateral edges. The boat hull also includes a lower hull surface outboard of the lateral edges of the running pad. Portions of the lower hull surface are above the water when the boat is at planing speed.
As mentioned above, the extrusion process produces a running surface with relatively sharp lateral edges. These sharp edges allow water migrating from beneath the lower planing element to break cleanly away from the edges, resulting in reduced hydrodynamic drag and improved boat performance. In a preferred embodiment, the lateral edges have a radius of curvature of less than about forty thousands of an inch (0.040 inches).
The lower planing element may be formed with a slight Vee angle. The Vee angle could be centered along the boat""s centerline and become progressively deeper at the second end of the running surface. The Vee angle can become progressively deeper starting at the first end of the running surface, or the contour of the running surface may remain unchanged for some distance from the first end before becoming progressively deeper.
The present invention also provides a method for manufacturing an aluminum boat with a bow, a transom, a centerline, and an undersurface in contact with the water when the boat is at rest. The method includes extruding an aluminum running pad like that described above, and attaching the extruded aluminum running pad to the boat""s undersurface with the lateral edges substantially parallel with the boat centerline and symmetrically offset therefrom.